1. Field of the Invention
This invention relates to an apparatus for generating a stream of water in a closed area, such as a lake, pond, tank, pool, harbor, or fish farm, to promote the flow of water and purify it.
2. Description of the Prior Art
A known apparatus for generating a stream of water is schematically shown in FIG. 24 of the accompanying drawings. The apparatus includes a hollow cylinder 02 held in an upright position by a buoy 010, a wall surrounding the cylinder 02 at its lower end and defining an air chamber 07 which is open at its bottom, a sinker 09 to which the cylinder 02 is moored by ropes 08, and a pipe 03 connected to the air chamber 07 for supplying compressed air thereinto. Compressed air is intermittently supplied into the air chamber 07 to build up a layer of air therein until the air flows over the lower end of the cylinder 02, enters it and forms a large mass of bubbles therein. As the bubbles rise, an upwardly flowing stream of water is created through the cylinder 02, so that the water staying near the bottom of a body of water in which the apparatus is installed is be replaced by a downwardly flowing stream of water.
The movement of water by the apparatus as shown in FIG. 24 is, however, not only intermittent, but also, as a rule, only vertical. Although a horizontally diffused stream is produced near the surface of the body of water, it is a secondary stream produced by the particles of the rising water striking against the air above the surface of the body of water, and is, therefore, too weak to perform any effective horizontal stirring of water.
Another known apparatus is shown in FIG. 25(a). It comprises a hollow cylinder 02 connected to a water tunnel, a drive shaft 015 which is rotatable by an electric motor, or other prime mover, a bevel gear device 016 connected to the drive shaft 015, a shaft 017 which is driven by the bevel gear device 016, an impeller 014 which is driven by the shaft 017 to generate a stream of water, and a strut 023 securing to the cylinder 02 a nacelle housing the bevel gear device 016, etc. A modified form of apparatus is shown in FIG. 25(b), and includes an electric motor 024 connected to the shaft 017, and a set of cables 025 connected between the motor 024 and a power supply.
The apparatus as shown in FIG. 25 (a) or (b) is used with, for example, a ship, or a machine for civil engineering work in water, and can produce a stream of water flowing in any desired direction including vertical or horizontal. It is, however, a complicated apparatus including a prime mover and other precise driving devices, and is, therefore, often difficult to use for a long time under water, as at the bottom of the sea. Moreover, it cannot aerate water, as the water which is caused to flow does not effectively contact air.